Microfibrous polyurethane sheets are known in the art as leather substitutes having good properties of softness and crease and, in the case of the abraded surface type, also of smoothness and suede or velours-like touch. Examples of such products and of their preparation are disclosed e.g. in U.S. Pat. Nos. 3,531,368 and 3,889,292 and in UK patent N. 1,329,710.
These known leather substitutes have been extensively used in the field of clothing. However these products have many drawbacks when used in other fields such as trimming in autovehicles and furniture, where their mechanical properties make them unsuitable for this application.
In the art it is known, e.g. in italian patent applications No. 21457-B/89 and No. 21457-B/89, the basic idea of improving the microfibrous imitation leather properties by forming a laminate of the base sheet and one or more functional substrates.
By functional substrate is meant a separately prepared substrate such as knitted or woven fabric, expanded polymer foam, waterproofing films, paper, etcetera. More than one substrate may be adhered to the same base sheet of imitation leather.
While the idea looked easy to implement, serious problems were encountered in order to meet the physical requirements of most demanding uses, such as trim covers for autovehicles. These problems led to modify the composition of the base sheet, and eventually to substitute polyurethane with other elastomers, e.g. chloroprene rubber, acrylic rubber etc., according to the end use of the laminated material.